1. Field of the Invention
The present invention relates to a control system of a galley installed in an aircraft.
2. Description of the Related Art
Conventionally, there are various galley-mounted equipments (hereinafter referred to as “insert equipments”) disposed in a kitchen facility (hereinafter referred to as “galley”) on an aircraft. The respective insert equipments have their own dedicated control panels, and the equipment is usually manipulated through the control panels. Therefore, it was not possible to provide control commands integrally for controlling the multiple insert equipments, or to monitor the insert equipments collectively. Therefore, a control system for correctly controlling these insert equipments in a short time in a prompt manner is desired.
However, in order to realize such a control system, it is necessary to constitute a certain communication system within the aircraft so as to enable frequent exchange of information between the respective insert equipments and the controller (display/control panel). Since the existing control system installed in the aircraft is subjected to complex and bothersome aviation communication restrictions, it was not easy to constitute a communication system between the insert equipments and the controller.
Therefore, a local communication network is to be constructed in order to establish an information and telecommunication with which the controller monitors and operates the insert equipment. It is expected that such galley control system is to be constructed into aircraft.
A proposal to adopt a Controller-area network (CAN bus) as a communication means for a galley control system of an aircraft has been deliberated in ARINC (ARINC project paper 812; Definition of Standard Data Interfaces for Galley Insert (GAIN); Equipment; CAN Communications), but it has not yet been officially announced. In the proposal of ARINC specification 812, a galley data bus network is constructed between insert equipments and a master galley control unit (MGCU) as master via a CAN bus interface for performing mutual communication and exchanging information, and necessary information is communicated with the aircraft system by connecting to the communication network of the aircraft via the MGCU. Special attention is given to the point that a peak of the total consumption power at meal time during which all the insert equipments are used at the same time can be reduced and dispersed by adjusting the start time of operation of the insert equipments through the network, which is considered to be an indispensible method for reducing the capacity of the generator disposed on the aircraft and saving energy.
There is another proposal related to utilizing the network of the galley data bus as a local network for controlling the insert equipments within the galley. Such art can be realized by additionally providing a CAN bus interface to the insert equipments, arrange a CAN bus wiring within the main body of the galley and disposing a MGCU additionally.
On the other hand, along with the diversification of lighting devices, much attention is recently given to an illumination light communication system that does not use the CAN bus interface. Japanese patent application laid-open publication No. 2008-271317 (patent document 1) discloses an example of an illumination light communication system enabling a large amount of data to be transmitted at high speed. According to the disclosed illumination light communication system, a transmitter emits modulated light that is modulated in accordance with data to be transmitted from an organic electroluminescence (EL) light source (commonly known as “OLED”: organic light-emitting diode). A receiver receives the modulated light emitted from the OLED, converts the received light into an electric signal and demodulates data from the converted electric signal. Since the system adopts an organic EL element formed of a material having a high speed response performance as the illumination light source of the illumination light communication system, the system can increase the amount of data transmission per unit time compared to a white light-emitting diode (LED), for example, and can transmit a large amount of data at high speed.
Further, Japanese patent application laid-open publication No. 2003-115803 (patent document 2) proposes a light emitting device and a communication system including the same, in which the communication speed is accelerated in a communication using light. According to the communication system, the light emitting device is provided with a light emitting element capable of transmitting signal light composed of light modulated on the basis of input data, the light emitting element being an EL element. Further, the light emitting element emits non-signal light composed of non-modulated light and signal light in different periods, wherein the non-signal light also functions as illumination. Further, the signal light also functions as illumination. Moreover, a means for storing transmitted information is connected to a light receiving element, for storing and writing in transmitted information.
Further, Japanese patent application laid-open publication No. 2008-227944 (patent document 3) proposes a receiver for visible light communication which does not require supply of power, and a visible light communication system using the same. Data transmission equipment modulates the driving current of lighting element (LED) with the received data, and changes the level of the light of LED according to the driving current. The data receiver detects the received illumination light from a change of output of a solar cell panel, demodulates this detected signal, and displays the demodulated data on a display section.
On the other hand, a communication system using infrared light is widely used in private households. Recently, much attention is given to visible light communication using visible light, along with the widespread use of illumination equipments using elements having good optical response such as LED and OLED. Visible Light Communications Consortium (VLCC) and Infrared Data Association (IrDA) have published on Mar. 6, 2009 a “visible light communication standard” version 1.0 compatible with the IrDA communication system.
In order to realize a control system for controlling insert equipments used within the galley, it is necessary to construct some type of control system as proposed in ARINC specification 812 and to enable frequent data exchange between the respective insert equipments and the controller (display/control panel) disposed on the aircraft. However, the controller disposed on the aircraft already has a constructed network for performing control operation of the aircraft, and in order to communicate with this network and exchange information with the aircraft, it is necessary to design a system satisfying the aviation communication regulations and having a high reliability. However, such control system integrated with the aircraft system could not be realized easily at a low cost.
On the other hand, a system having given up the communication with the aircraft system and constructed as a network using a CAN bus as a local communication system, such as the one proposed in ARINC specification 812 for enabling communication between the insert equipments within the galley and a controller, a failure caused by wire connection may occur. The respective electronic equipments including the network environment within the galley must satisfy a series of regulations regarding a sequence of typical environment testing conditions determined to comply with aviation regulations, such as an RICA/DO•160 standard specification determined by the special committee of the Radio Technical Commission for Aeronautics. Especially in section 21.0 of RICA/DO 160, there is a standard specification regarding radio frequency (RF) energy emission which restricts radiated RF emission and conducted RF emission of electromagnetic noises leaking from electronic equipments, and at present, much work and costs are required to comply with this regulation. The CAN bus interface is not an exception and the regulations related to the standard specification of radio frequency energy emission cannot be avoided easily.
As described, there are various problems to be solved in designing a simple and inexpensive network system, and such system has not yet been realized. We consider that the construction of a wireless communication network that does not use any wired electric signal communication is most appropriate as a galley control system. Optical communication using no wires is considered to function sufficiently within the narrow galley space. In order to perform mutual communication between the insert equipments and the controller, it is necessary to realize a mutual direction communication using two kinds of lights. For example, a visible light and an infrared light can be used.